Turbochargers are used to enhance performance of otherwise normally aspirated internal combustion engines. They are typically centrifugal compressors driven by exhaust gas turbines that boost engine power, curtail emissions, and improve fuel economy. Rather than being belt-driven by the engine, as are superchargers, the typical turbocharger relies only upon exhaust energy for its power, and as such is designed to rotate at speeds considerably higher than those of superchargers.
The challenges of satisfactorily lubricating turbochargers are well known by those skilled in the art. Normally a single shaft connects an exhaust driven turbine wheel to a compressor wheel. The shaft is journaled within a pair of spaced sleeve bearings along its length, and includes a shoulder at the compressor wheel end configured to support a thrust bearing. At the thrust bearing end, an oil flinger and an oil deflector are designed to work in concert to drive oil away from piston rings secured about the shaft by keeping the bulk of the oil on the thrust bearing side of the deflector. As such, lubrication oil sealing systems are generally designed to avoid any oil leakage past the piston rings; i.e. to minimize chances of oil entering the compressor section of the turbocharger.
Turbochargers can spin well over 100,000 RPM. Numerous enhancements have been made to increase their longevity, particularly as related to issues of lubrication. For example, ceramic bearings have been used in some applications, while various improvements in oil circulation have been achieved in others. As packaging requirements have continued to reduce physical spaces allotted to under-the-hood components including turbochargers, however, additional improvements related to oil flinger and oil deflector componentry are needed to assure continued effectiveness of turbocharger oil sealing systems.